Tool for lapping valve seats



Feb. 4, 1936. BERKMAN 7 2,029,753

* TOOL FOR LAPPING VALVE SEATS Filed July 21, 1934 Patented Feb. 4, 1936 OFFICE TOOL FOR LAPPING VALVE SEATS Herbert A. Berkman, Chicago, Ill., assignor to Zim Manufacturing Company, a corporation of Illinois Application'July 21, 1934, Serial No. 736,279

8 Claims.

In the modern automobile engine the valve seats are usually composed of metal of such hardness that refinishing of the same must be done by lapping instead of by an ordinary grinding operation in which an abrasive material is placed between a valve and its seat and the valve is turned about its axis; special tools being required to perform the lapping operations. The object of the present invention is to produce a simple, novel and efficient tool for lapping such valve seats.

Lapping can best be done by a tool having a head provided with a face similar to the face of the valve that is to cooperate with the seat to be treated. This face of the head of the tool should be relatively soft, since otherwise it would simply slide over the lapping compound without producing any material effect on the valve seat. Being soft, the material wears away rather quickly. Where the head of the tool is in the form of a solid block for the purpose of providing the desired rigidity and preventing distortion of the working face, the entire head must be discarded after only a comparatively small amount of wear has taken place. The present invention may be said to have for its object to overcome the need for discarding an entire head of a tool of this type by making it possible to provide the head with a new wearing face at only a slight cost.

To this end, I provide the tool, comprising a head and a stem or pilot, with a detachable shell that constitutes a wearing face for the head; the parts being rigidly united so that the shell and the head act substantially as one integral element in the performance of a lapping operation, but may be quickly and easily separated so as to replace a worn shell or facing.

The various features of novelty whereby my invention is characterized will hereinafter be pointed out with particularity in the claims; but, for a full understanding of my invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 is a central longitudinal section through a lapping tool embodying the present invention; Fig. 2 is a top plan view; and Fig. 3 is a view showing the several parts of the tool separated from each other, one above the other, all of the parts except the conical shell or facing member and the washer, which are shown in section, bein'gin elevation.

My improved tool, as a whole, comprises a stem or pilot I that is preferably similar to the stem of the valve whose seat is to be lapped, so that it may serve as a pilot or centering device for the tool; together with a head on one end of the stem or pilot. In the arrangement shown, 2 5 represents the head, or rather the body member of the head. Cooperating with the member 2 is a cup-shaped shell 3 into which the member 2 fits and which forms a solid, rigid backing for all parts of the working areas of the shell; 10-1 The members I, 2 and 3 may be united in any desired way. In the particular arrangement shown in the drawing, a section of the stem at one end of the latter is of reduced diameter and screw-threaded, as indicated at 4. Thus the stem 15 is left, at the inner end of the screw-threaded part or section thereof, with an annular shoulder 5 that faces outwardly toward the corresponding end of the stem. Loose on the screw-threaded part is a thick, stiff washer 6 which rests on the. 20 shoulder 5 and, in turn, provides for the shell or facing member 3 a bearing face or seat of considerably larger area than the face 5. The member 2, which is frusto-conical, has an axial screwthreaded bore 1 to receive the screw-threaded part 4 on the stem or pilot. The shell or wearing member 3 is a frusto-conical cup into which the member 2 fits snugly, the cup having in the bottom wall an opening 3 through which the screw-threaded part 4 on the stem freely passes. I prefer that the part of the member 2 which is housed within the shell be truncated to a some what greater extent than the shell itself, so as to prevent it from coming in contact with the flat bottom of the shell. Consequently, when the parts are assembled, as shown in Fig. 1, the screwing-down of the member 2 causes the same to be pressed firmly into the shell in a manner tending to expand the latter; thereby insuring a perfect contact between the members 2 and 3 40 throughout the entire length and breadth of that portion of the shell lying between the plane of the top or mouth of the cup and the plane of the lower end of the member 2.

The member 2 may be composed of any suitable metal since it is not subjected to any abrading action, whereas the shell or facing member 3 should be made from metal that is much softer than the valve face to be operated upon. In actual practice satisfactory results have been obtained by using soft steel as the material for the shell or facing member. A simple and inexpensive manner of manufacturing the cup-shaped shells or facing members is to stamp them out of sheets or thin plates of soft steel, thereby bringing the cost thereof, when made in large quantities, only slightly above the actual cost of the sheet or plate material.

The tool may, of course, be manipulated in any 5 suitable Way to lap a valve seat. I prefer to provide the top face of the member 2 with recesses,

such as indicated at 9, 9, to be engaged by the operating member of an ordinary valve-grinding tool. With this arrangement, after the parts of the lapping tool have been assembled, the tool is simply substituted for the valve that ordinarily cooperates with the seat, a suitable lapping compound being interposed between the head of the tool and the valve seat, and the toolis then turned in the usual or customary way.

When the working face of the tool is believed to have become slightly worn, it may be renewed by simply unscrewing the head, throwing away the cup-shaped shell, and applying a new shell.

Thereupon, after the parts are again screwed together, the tool is once more ready for use.

While I have illustrated and described with particularityonly a'single preferred form of my invention, I do not desire to be limited to the exact structural detailsthus illustrated and described; but'intend to cover all forms and arrangements which come within the definitions of my invention constituting the appended claims.

I claim:

1. A tool for lapping valve seats, comprising a stem, astifLsmooth, continuous cup-shaped shell ofmetal, anda block fitting into the shell; the stem, the shell and the block being detachably connected together incoaxial 1 relation toeach other into a single rigid unit.

2. A tool for lappingvalve seats, comprising a stem having at one end a screw-threaded portion and an outwardly-facing shoulder inwardly from the screw-threaded portion, a stiff; smooth, continuous cup-shaped frusto-conical metal 'shell having-in the bottom=an opening to permit the passage of the screw-threadedportion of the stem and permit the shell to rest on said shoulder, and

4535a frusto-conical block shaped to fit into the shell and'having 'an axial screw-threaded base to receive the screw threadd portion of th'e'stem and 3? Atool for lapping valve seats, comprising a stem" having at" some distancefrom one en'd a shoulder facing: towardsaid end," a stiff, smooth,

continuous cup-shaped frusto-conical metal shell having in the center of the bottom a hole to permit the passage of the stem and allow the shell to rest against said shoulder, a rigid filler block adapted to fit into the shell, and cooperating ele- 5 ments on the block and stem to enable the block to hold the cup against the shoulder and unite the stem, the shell and the block into a rigid unit.

4. A tool for lapping valve seats, comprising a 10 stem and a head; said head including a detachable, stiff, smooth continuous, frusto-conical metal shell.

5. A tool for lapping valve seats, comprising a stem and ahead, said head having a rigid body 15 portion and a detachable wearing part in the form of a stiff, smooth continuous frusto-conical metal shell.

6. Atool for lapping valve seats, comprising a stem and a head, said head having a rigid body 30 p'ort'ion"and 'a detachable Wearing part in the form of 'a'stiif' frusto-conical shell of soft steel' having a smooth uninterrupted peripheral face.

7. A toolfor lapping valve seats, comprising a stem having at one end a screw-threaded portion 25 and an outwardly-facing shoulder inwardly from the screw-threaded portion, a stiff, smooth, con"- tinuo'us cup-shaped frusto-conical metal shell having in the bottom an opening to permit the passage of the screw-threaded portion of the stem 30 and permit the shell to rest on said shoulder, and a -frusto-conical 'block shaped to fit into the shell and havin'gf an axialscrew-threaded base toreceive the screw-threaded portionof the stem and clamp the. shell between the block andthe said 35 shoulder, the block being truncated to a greater degree than the shell whereby the block standsclearoftthe bottom of the shell.

81 A tool for lapping valve seats, comprising a stem having at some distance from one end a 6 shoulder facingtowardsaid end, a still cup-- shapedfr'usto-conical metal shell having in the center'of the bottom a hole to permit the passage ofth'e stem' and allow the shell to rest against said shoulder, a rigid fillerblock'adapted" 5'- to fit into the shell and truncated to a greater degree'than the shell, and cooperating elements on the block and stem to enable the block'to hold" the cup against the shoulder andunite the stem;

the shell and the block into a rigid unit: 50

HERBERT A. BERKMAN-' 

